850 1995 Jetronic suitable MAF harness, and code 411 TPS signal, when running rich

classical · Post by **classical** » 19 Nov 2025, 13:31

Greetings!

First of all, I love the respectful atmosphere of the Forum of the Matthew's Volvo Site and the DIY spirit here. It is enjoyable to read the forum posts and to discuss in this forum (although I have not discussed much).

Now, to the actual issues; and I appreciate the time you guys take to answer the questions of us newbies. My 1995 N/A 850 is running rich, and soon I will check the fuel pressure and if the injectors are clogged (I just have to wait for the fuel pressure gauge to arrive). I have checked vacuum leaks and did not find any (at least with the old brake cleaner test). However, the car also threw some codes, namely A2: 121 - MAF sensor signal; A6: 214 - Engine speed (RPM) sensor signal missing sporadically, and 411 - Throttle position sensor (TPS) signal from fuel injection system. Earlier it threw A2: 411 - TP sensor signal. So, I replaced the TPS.

Regarding 121: I tested the terminals of the MAF sensor harness (using this guide: https://www.volvoclub.org.uk/tech/servi ... nTurbo.pdf), and terminal 2 gave 1.4 ohms, and terminal 1 gave 25.3 ohms. Terminal 3 gave no voltage. I forgot what terminal 4 gave, and I will check again if needed, but am I right that these results alone show that I might need a new harness and cable for the MAF sensor? By the way, I cleaned the harness before the measurements. I also cleaned the MAF sensor, and I guess the sensor itself is good, because when I drive with it unplugged, the RPMs go crazy.

Since my Volvo has LH 3.2 Jetronic, do the harness and the cable have to be from a car with LH 3.2 Jetronic or can they be from Motronic, as well?

Regarding 214: I will check the ohms of the RPM sensor, which is the crankshaft sensor if I have understood correctly. And I will check that the wires are far from the spark plug wires. Any other suggestions regarding what to do with this code?

Regarding 411: I will check the signal of the TP sensor, but when it says that a signal from fuel injection system is the problem, what other things should I consider here? Should I also test the signal of the harness/cable into which the TP sensor plug is plugged? When I checked the injectors with the multimeter, they were fine. So, as I said, I will check if the injectors are clogged. But what other things regarding the injectors or the injection system could be the problem here?

Post by **abscate** » 20 Nov 2025, 01:24

Welcome Finland! I don’t know much about the early FIJ systems so we need to wait for the other folks to wake up in your 1995.

classical · Post by **classical** » 20 Nov 2025, 02:10

Hello Denmark!

While we are waiting for comments, I'll give more info. I just measured signals from the TPS harness, and got the following (as the harness is as it is when unplugged; in other words, as it is "upside down"): Left 0.32 volts; center 0.37 volts; right (the ground) has continuity. What do those readings tell someone?

classical · Post by **classical** » 21 Nov 2025, 03:54

More updates: I tested the signal of the RPM sensor and it was within the spec: 270 ohms. Right? However, the harness did not give any reading. Should it? The fuel pressure gauge arrived, and I tested the fuel pressure, and it was 32 psi, which is too low, as I have understood it. I also tested the fuel injectors with the injector tester and none of the injectors gave any reading, namely the pressure did not drop or the pointer did not move at all. I wonder if the gauge or the injectors are bad or did I do something wrong, I do not know. How could all of the injectors be bad? I followed the instructions of this video: The gauge did make the buzzing noise and all.

Please help, someone, if you can.

classical · Post by **classical** » 22 Nov 2025, 20:07

Oh, there was an answer to the question about the fitting of Motronic MAF harness to Jetronic in here: viewtopic.php?t=90421. They do not fit. So, sorry for that question then.